British journal of anaesthesia
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Comparative Study Clinical Trial Controlled Clinical Trial
Choice of opioid for initiation of combined spinal epidural analgesia in labour--fentanyl or diamorphine.
Sixty-two women requesting regional analgesia in labour were allocated to receive a 1.5 ml intrathecal injection as part of a combined spinal-epidural (CSE) analgesic technique. This contained either bupivacaine 2.5 mg plus fentanyl 25 microg (group F) or bupivacaine 2.5 mg plus diamorphine 250 microg (group D). Times of analgesic onset and offset were recorded, motor and proprioceptive assessments made and side-effects noted. ⋯ Maternal hypotension, pruritus, proprioceptive loss, nausea and fetal bradycardia were rare and not severe, and their incidences did not differ between groups. No respiratory depression was observed after CSE. This use of diamorphine was not associated with increased side-effects compared with fentanyl/bupivacaine, and it has a longer duration of action.
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Transoesophageal echocardiography (TOE) has gained widespread acceptance among cardiac anaesthetists as a tool to facilitate peri-operative decision-making. This observational study analyses the impact of TOE and its inter-observer variability on intra-operative patient management during cardiac and major vascular surgery. From June 1996 to December 1998, standardized reports were obtained from 11 anaesthetists in 1891 adult cardiac and vascular surgery patients undergoing routine biplane or multiplane TOE. ⋯ There was no significant difference in the case mix between observers. TOE had an important impact on intraoperative patient management. Inter-observer variability was significant for several variables but not for the frequency of additional surgical procedures.
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Ocular microtremor (OMT) is a fine high frequency tremor of the eyes caused by extra-ocular muscle activity stimulated by impulses emanating in the brain stem. Several studies have shown that the frequency of this tremor is reduced in patients whose consciousness is reduced by anaesthesia or head injury. Therefore, OMT may possibly be used to determine depth of anaesthesia. ⋯ OMT activity was reduced progressively at predicted plasma concentrations of propofol of I and 2 microg ml(-1) and then plateaued between 3 and 5 microg ml(-1). There was a significant difference between the last awake OMT recording and the first recording at loss of consciousness (P < 0.001). OMT recording holds promise as a practical indicator of the depth of anaesthesia.
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We investigated the relationship between the latency of the Nb wave of the auditory evoked response (AER) and periods of awareness during propofol anaesthesia. In the anaesthetic room before cardiac surgery the AER was recorded continuously in 14 patients. Awareness was measured by the ability of the patient to respond to command using the isolated forearm technique (IFT). ⋯ None of the patients had any recollection of events after the initial induction of anaesthesia as measured by explicit and implicit memory tests. These results suggest that the Nb latency of the AER may represent an indication of awareness in individual patients, but wide inter-patient variability limits its practical usefulness. In addition, because no evidence of memory was demonstrated, even when patients were known to be awake, the relationship between AER and memory processing remains unclear.
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Many indices are used to quantify pulmonary oxygen transfer. Indices that use only measurements from arterial blood and inspired gas assume a constant C(a-v)O2. Though variations in C(a-v)O2 are recognized, indices such as PaO2/FIO2 remain popular and are often considered the best measure of pulmonary oxygen transfer in critically ill patients. ⋯ At an FlO2 of 0.7, PaO2 /FIO2 varied between 18 and 10 kPa and at an FIO2 of 0.9 the ratio varied between 22 and 8 kPa. These changes, which were unrelated to underlying lung pathology, are sufficiently large to result in misclassification on the gas exchange scale suggested by the American European Consensus Conference on ARDS. This study shows there is no reliable alternative to Qs/Qt to quantify pulmonary oxygen transfer in critically ill patients.